Heretofore, techniques for improving the stability of the images to be reproduced in silver halide color photographic materials and for improving the image quality of the reproduced color images (especially, the graininess and the sharpness thereof) have been desired, and various studies and developments have been made for these purposes. In particular, since the intended levels of the graininess and the sharpness of duplicating color photographic materials are high, it is necessary to plan the photographic materials by using silver halide emulsions of extremely fine grains. The use of silver halide emulsions of extremely fine grains brings about not only the improvement of the graininess of the photographic materials but also the improvement of the sharpness of them as reducing the degree of scattering of light in the photographic materials. Therefore, the use of such fine silver halide grains is extremely favorable from the viewpoint of improving the image quality of the color images to be reproduced in the photographic materials.
However, the use of silver halide emulsions of fine grains in producing color photographic materials so as to improve the image quality of the color images to be reproduced in the photographic materials has caused an additional problem. Precisely, when silver halide emulsions of fine grains having a grain size of 0.25 .mu.m or smaller was used in preparing color photographic materials, the graininess and the sharpness of the photographic materials were surely improved, but, surprisingly, it has been found that when the photographic materials were exposed, allowed to stand and then developed, the sensitivity of the photographic materials was noticeably lowered as compared with the photographic materials that were developed immediately after their exposure. For this reason, it was indispensable to develop the technique capable of improving the keeping quality, in particular, the variation of the photographic properties of the exposed photographic materials with the lapse of time, in addition to the technique for improving the graininess and the sharpness of the photographic materials.
Regarding the improvement of the graininess and the sharpness of color photographic materials, JP-A-62-99751, JP-A-4-217242 and JP-A-4-275544 (the term "JP-A" as used herein means an "unexamined published Japanese patent application") have disclosed techniques of using silver halide grains having a relatively small grain size. Specifically, these publications mention techniques for further improving the graininess and the sharpness of photographic materials by using silver halide emulsions of fine tabular grains and also techniques for improving the gradation and the color reproducibility of photographic materials, in addition to the graininess and the sharpness thereof, by modifying the layer constitutions of photographic materials and by using diffusive DIR compounds along with such fine grains. However, these have no description relating to the technique for improving the keeping quality of the photographic materials containing fine silver halide grains, especially for overcoming the lowering of the sensitivity of the photographic materials containing silver halide emulsions of fine silver halide grains which were exposed, stored and then developed. The inventor of the present invention has found for the first time that the sensitivity of the color photographic material containing fine silver halide grains is specifically lowered if the photographic materials are stored after exposure.
Further, JP-A-60-12540 discloses a silver halide photographic material comprising Lippmann-type silver halide grains having a grain size of 0.10 .mu.m or smaller and a bisphenol derivative. However, the technique as disclosed in JP-A-60-12540 relates to improving the keeping quality of black-and-white image after black-and-white development, which is quite different from the technique of the present invention which relates to improving the stability with the lapse of time of photographic property of the exposed color photographic material to vary before processing.
Given the situation, it is desired to attain the technique capable of further improving the storage stability of the color photographic materials containing fine silver halide grains, in addition to improving the graininess and the sharpness thereof, for the purpose of satisfying the recent users' demands that they want to have easily handlable high-quality photographic materials.